1. Field of the Invention
The instant invention relates to application of adjuvants to fabrics in tumble-dryer automatic dryers. More particularly, it relates to an article in the form of a flexible substrate carrying a fabric conditioning composition.
2. Related Art
Silicones have been applied to fabrics during manufacture of fabrics or during the make up of articles of clothing using processes such as padding or spraying. With respect to application of silicones to fabrics during a laundry process, Great Britain Patent Application No. 1,549,180; Burmeister et al., U.S. Pat. No. 4,818,242; Konig et al., U.S. Pat. No. 4,724,089; Konig et al., U.S. Pat. No. 4,806,255; Dekker et al., U.S. Pat. No. 4,661,267 and Trinh et al., U.S. Pat. No. 4,661,269 describe aqueous dispersions or emulsions of certain silicones of limited viscosity incorporated in liquid rinse-cycle fabric softening compositions. The disclosed compositions are rinse-cycle aqueous dispersions. A fabric softening composition containing emulsified silicone combined with conventional cationic softening agent is also taught by Barrat et al. in U.S. Pat. No. 4,446,033. The compositions are taught for use during the aqueous rinse cycle of a laundry process. The rinse compositions taught by the '089, '255, '267 and '269 patents contain cyclic amine fabric softening agents and employ water-soluble Bronsted acids to control the pH of the aqueous compositions for proper dispersion of the amine.
The compositions disclosed in the art contain individual particles of a silicone and individual particles of a fabric softening agent.
Wells, U.S. Pat. No. 4,308,024 discloses non-silicone fabric softening compositions consisting essentially of a water-insoluble cationic detergent surfactant and a C.sub.8 -C.sub.24 alkyl-or alkenyl monocarboxylic acid.
The application of fabric softeners to fabrics in the tumble dryer by use of a flexible substrate carrying the fabric softeners is known in the art. The advantages of dryer added fabric conditioning include a more convenient time of addition in the laundry process and avoidance of undesirable interaction of softening agents with detergents.
Rudy et al., U.S. Pat. No. 3,972,131 discloses dryer sheets including a silicone oil as an ironing aid. Kasprzak et al., U.S. Pat. No. 4,767,548 discloses the use of certain silicones in dryer sheet formulations.
Coffindaffer et al., U.S. Pat. No. 4,800,026 discloses curable amine functional silicones in fabric care compositions.
Japanese Patent 62/78,277 discloses chemically combined condensation products of amino modified silicone oil as softeners.
In the manufacture of the dryer added fabric conditioning sheets described in the references mentioned above, when silicones are mixed with fabric softeners, the resulting mixtures are non-homogeneous and phase separation occurs readily. The homogeneity of such mixtures is ensured only by continuous vigorous agitation. An additional problem associated with the use of a nonhomogeneous mixture is the separation of actives at the point of application of the active mixture on the substrate resulting in unevenly impregnated sheets.
Bronsted acids described herein compatibilize aminosilicones with fabric softening agents. Critically, the aminosilicones in the compatible mixtures of the present invention do not separate from the fabric softening agent during coating or solidifying of the dryer sheets. Thus, the present invention affords easier processing of dryer added fabric conditioning sheets. Additionally, even and uniform distribution of the actives on the dryer sheet can be attained, alleviating the problem of unevenly impregnated sheets.
Accordingly, it is an object of the present invention to provide an article which provides for release of a fabric conditioning composition within an automatic laundry dryer, the composition containing a compatible mixture of a fabric softening component, an aminosilicone and a Bronsted acid.
These and other objects and advantages will appear as the description proceeds.